Testing the James Webb Space Telescope Primary Mirror

JWST in-process optical testing and cryogenic requirement compliance certification, verification andvalidation was probably the most difficult metrology job of our generation in astronomical optics. But, the challenge was met: by hard work of dozens of optical metrologists; development and qualification of multiple custom test setups; and several new inventions, including 4D PhaseCam and Leica Absolute Distance Meter. This paper summarizes the metrology tools, test setups and processes used to characterize the JWST primary mirror.